It is known to improve mechanical properties such as tensile strength, bending strength, impact strength and the like and heat resistance of polyolefins by incorporating thereinto reinforcing materials such as glass fiber and the like. However, such mechanical properties and heat resistance of polyolefins are not sufficiently improved by merely incorporating thereinto glass fiber because there is attained no bonding power therebetween, and hence it is not possible to obtain such effect of improvement as may be obtained in the case where glass fiber is incorporated into unsaturated polyesters having in the molecule polar groups, or into epoxy resins.
On one hand, there are proposed various processes for improving bonding power between polyolefins and glass fiber. For instance, Japanese Patent Publn. No. 41096/1974 discloses a process in which maleic acid or maleic anhydride, polyolefin and glass fiber subjected to surface treatment with aminosilane type compounds are allowed to undergo reaction at a temperature higher than a melting point of the polyolefin in the presence of organic peroxides. Further, Japanese Patent Publn. No. 31895/1977 discloses compositions comprising polyolefins, modified polyolefins having aromatic carboxylic acid anhydride units and glass fiber subjected to surface treatment with aminosilane type compounds. Still further, Japanese Patent Publn. No. 10265/1976 discloses a process for preparing compositions comprising modified polyolefins obtained by melt kneading in an atmosphere of nitrogen polyolefins and maleic anhydride in the presence and glass type reinforcing materials, or compositions comprising above-mentioned components and unmodified polyolefins. The processes and compositions as proposed above have their respective effects in their own ways.
Recently, however, there is a strong and growing demand for so-called engineering plastics, i.e. heat-resistant thermoplastic resins which are more excellent in heat resistance, and that in mechanical strength, and hence it is not desired that a further improvement is made in the above-mentioned compositions which are all found to be still insufficient in heat resistance and mechanical strength. Japanese Patent Publn. No. 9943/1981 discloses, as one example of such improvement as desired above, polyolefin resin compositions comprising (A) polyolefin resins added with unsaturated carboxylic acid or polyolefin resins added with unsaturated carbolylic acid diluted with polyolefin resins, (B) nitrogen containing resins and (C) fillers, and it is alleged that by virtue of incorporating into polyolefin resin compositions of the nitrogen containing resins, the polyolefin resin compositions obtained thereby are found excellent in mechanical strength, heat resistance, coatability and the like. However, it has been found that even when ABS or nylon 6 concretely disclosed in the said publication is incorporated into polyolefin having a melting point of above 200.degree. C., for example, poly-4-methyl-1-pentene, which is particularly excellent in heat resistance among other polyolefins, heat resistance of the resulting polyolefin resin composition is not improved at all, or rather, decreases when ABS or the like is incorporated thereinto.
Japanese patent L-O-P Publn. No. 53549/1985 filed by the present applicant discloses that compositions comprising poly-4-methyl-1-pentene, unsaturated carboxylic acid graft modified poly-4-methyl-1-pentene, nylon 66 and inorganic fiber are excellent in heat resistance and mechanical strength in comparison with fiber reinforced polyolefin resin compositions proposed prior to the filing date of said publication. On studying further the compositions disclosed in said publication, however, the present applicant has found that said compositions are relatively high in water absorption properties due to the presence of nylon 66, and there is a fear of decrease in mechanical strength of the resulting compositions by moisture absorption thereof.
The present invention is intended to solve such problems associated with the prior art as mentioned above, and an object of the invention is to provide fiber reinforced polyolefin compositions which are excellent in heat resistance as well as in water resistance, moisture resistance and solderability, and that excellent in mechanical strength.